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The operation was done by the method which Dr. Wyeth calls the ideal amputation at the hip-joint, and which he has described so well in his excellent papers in the Medical News. The following description is in his own words:

"In the formation of flaps the surgeon should be guided by the condition of the parts within the field of operation. When permissible, the following method seems ideal: About 6 inches below the tourniquet a circular incision is made, and this joined by a longitudinal incision commencing at the tourniquet and passing over the trochanter major. A cuff that includes the subcutaneous tissue down to the deep fascia is dissected off to near the trochanter minor. At about the level of the trochanter minor the remaining soft parts, together with the vessels are divided down to the bone by a circular cut, and in order to facilitate the search of the vessels, the soft parts are rapidly removed from the femur for several inches below the line of the divided muscle. At this stage of the operation the larger vessels, veins as well as arteries, should be tied with good-sized catgut. As suggested by Prof. Murdoch, of Pittsburgh, I now leave the entire extremity intact and use the full length of the limb as a lever in dislodging the head of the bone. Wnen the larger and more easily recognized vessels have been secured the muscular attachments to the upper extremity of the bone are lifted off with scissors or knife very close to the bone. Holding the soft parts away with retractors, the capsular ligament is exposed and divided in its circumference. Forcible elevation, abduction and adduction of the thigh permit entrance of air into the socket, and, at the same time rupture of the ligamentum teres, and the disarticulation is then easily effected."

When I first read Dr. Wyeth's description of the operation, I apprehended that the presence of the tourniquet might seriously interfere with the disarticulation, but no difficulty whatever was experienced in our case. We proceeded in the manner as described above, but owing to the invasion by the sarcomatous growth it became necessary to cut a considerable portion out of the cuff of skin and subcutaneous tissues anteriorly. The vessels were tied with silk. There was absolutely no loss of blood, except the small quantity which still remained in the limb; in fact, the loss of blood was not as great as is usual in amputations at any other part of the thigh. The acetabulum was packed with gauze, a large drainage tube placed in the upper end of the outer incision and the wound closed with silk-worm gut. There was considerable oozing from the wound during the first night. Shock was pronounced, and constant vomiting from the effects of chloroform tended to still further reduce the patient. At one time during the first

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night she seemed to be sinking, but rallied again towards morning. There was no further trouble, and recovery was rapid. The temperature never rose above joi 0, but remained between 990 and 100 ° for several weeks, No part of the flaps sloughed, and there is an excellent covering for the acetabulum. In seven weeks she was able to use her crutches a little, and her general health is now improving rapidly. There is no evidence at present, that the growth will recur.

Practical Bacteriology.

By E. B. LA FEVRE, M. D.; A BILENE, Kansas.

ARTICLE XII.-ANIMAL INOCULATIONS.

N ANIMAL inoculation we come to the last requirement laid down by

Koch for the determination of the pathogenetic properties of microorganisms. By the application of animal inoculation we are perfectly enabled to study the exact relations taking place between the animal on the one hand and the bacterium on the other. It may be said that this is the method conclusively proving the specificity of germ life. If we have found a certain micro-organism in the tissues of a certain animal, and we have, by the technical procedures heretofore described, isolated that microorganism, and obtained it in pure culture form, and we now inoculate some susceptible animal with this pure culture, and we have produced in the inoculated animal the same symptomatology and the same pathologic lesions that we found in the animal from which we originally obtained our germ, we may be absolutely sure that we have found the causative factor productive of the disease in question. So that in bacterial investigation we find that the inoculation of animals is a very important, if not the most important link in the chain of evidence which establishes the identity of a given microbe and show its relation to disease.

As time goes on animal inoculation assumes a greater and greater importance to the physician as a means of differentiating one disease from the other, and thereby establishing a more certain method of diagnosis; and I predict the medical man of twenty-five years hence will come to rely, in many instances, upon this means of permitting him to utter an absolute diagnosis of his cases.

Many animals have been used for inoculation purposes, among the inore important of which are: Rabbits, mice, guinea-pigs, rats, dogs, monkeys and certain birds and fowls.

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In the selection of animals for inoculation purposes there are generally two questions which are to be considered, viz, the cost and the susceptibility to the action of the germ under consideration. All animals are not equally susceptible to germ influences, and endeavor should always be made, whenever possible, to choose that one which reacts most favorably to the microorganism with which we are dealing. This forms an especially important consideration when original investigation is being carried on, where absolute and exact observations are strictly essential.

For diagnostic purposes it has been clearly shown that the ordinary white muuse forms the most generally suitable animal; as it is susceptible to a large number of the more important infectious diseases which afflict mankind. It is more or less receptive for glanders, tetanus, malignant odema, the various forms of septicemia, pyemic affections, etc., etc., as well as chicken-cholera, hog-cholera, splenic fever, etc. Other advantages in the use of the white mouse is its cheapness, the ease with which they are propagated, handled and inoculated.

Where it is desired to make the primary experiments in the bacterial investigation of almost any of the ordinary pathogenic processes, the use of white mice is usually sufficient.

Mice are best kept and propagated in small wooden boxes, say twentyfour inches long, twelve inches wide and eighteen inches deep, having a cover of a closely woven wire gauze held in place by some simple means.

This box should be filled about one-third full with fine sawdust, and over the top of the sawdust should be placed a thin layer of cotton-batting. The case is then ready for the reception of the mice. The mice burrow into sawdust forming their nests, and thrive and breed well. Fifteen or twenty mice can safely be kept in a box of the above size, and it is only required that the sawdust and cotton be changed once every two or three weeks. The sawdust also serves to take up the excrement of the animals, thereby allaying disagreeble odors and keeping the cage dry. The best food for mice consists of moistened white bread and oats or wheat.

When mice have been infected they must be isolated from the others, and at the same time it is generally desirable to have them so arranged that they can be closely observed. For this nothing answers a more admirable purpose than a Mason quart fruit jar, having a lid of wire gauze fitted over it and held on by tying or any other convenient manner. Each jar should be filled one-third full of the sawdust and the same care and food given it as when the boxes are used.

The manner of inoculating an animal and the point to be chosen for inoculation must always depend upon the experimental object in view.

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Usually the introduction of the virus through a slight wound of the skin is sufficient. In the case of mice, a small transverse incision just in front of the tail, and then tearing up the connective tissue so as to form a small pocket, and placing a small quantity of a pure culture in this pocket, is the method now practiced by almost all bacteriologists, where general infection of the animal is the object sought.

For inoculations such as the above, and unless some such operation as laparotony or trephining of the skull is necessary, anesthesia is not required as the operation is, to all intents and purposes, devoid of pain, and very quickly over with. Mice tolerate both chloroform and ether very well, indeed, and can be kept under the anesthetic for almost any desired length

On the other hand, guinea-pigs and rabbits react very badly to anesthetics, and it requires considerable experience in order to render them anesthetic without killing them. Mice and the smaller animals are best anesthetized by placing them together with a piece of absorbent cotton saturated with chloroform or ether under a bell-glass, or in a tightly-closed jar for a few minutes, when they readily succumb to the effects of the drug. In the case of rabbits and other larger animals, they must be first closely wrapped in a towel, leaving only the head exposed, and then administer the anesthetic by means of a cone. After rabbits have breathed the vapor for a few minutes, respiration will cease; at this point the anesthetic must be withdrawn, when after a little time, the breathing will be resumed. The cone should only be held over the head for such length of time as will just serve to keep up anesthetic action.

In the induction of anesthesia in animals the same rules and precautions should govern as obtain in the anesthetizing of man, except that allowance be made for any peculiar characteristics the animal may possess.

Inoculation through the skin may, if desired, be made by scarification (somewhat similar to vaccination of man) of the ear, or other part, after having clipped off the hair, and then rubbing in the virus, always taking the precaution to first thoroughly disinfect the parts with a carbolic acid solution. Or, subcutaneous inoculation may be made with a hypodermatic syringe. First having sterilized the syringe, mix the virus with a small quantity of sterile water or buillon, draw it into the syringe and inject into the subcutaneous connective tissue.

Intra-abdominal injections may be made with the hypodermatic syringe loaded in the same manner as for subcutaneous injections, and then pinching up the whole layer of the abdominal wall in a longitudinal direction, pass the needle entirely through both layers of the fold, then releasing the tissue held by the fingers, slowly withdraw the needle until it is within the

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abdominal cavity, and discharge the contents of the syringe. If the injection is correctly conducted in the above described manner, there will be no danger of injuring the intestines.

Sometimes, as for instance with tetanus, it is essential that the inocula tion be made under the meninges of the brain. If such is desirable, a small opening must be made with a trephine, through the skull of some animal the size of a rabbit or larger, and after making this opening through the bone, make a small incision through the dura mater with a scalpel, place in it the inoculating material, replace the incised dura, and carefully and closely stitch the overlying skin. The point usually chosen is midway between the ears, just above the eyes.

For intra-veinous injections some of the larger animals should be used. The rabbit, if susceptible to the virus to be used, makes a very eligible selection. Injection, with a sterile syringe, can be easily effected through the large vein running along the posterior border of the ear. The rabbit should be wrapped in a large towel, leaving only the head exposed, and placed on the lap of an assistant. Then thoroughly cleanse the whole ear with a two per cent carbolic acid solution. Let the assistant grasp the ear around its base and compress it sufficiently to produce an engorgement of the veins. Grasp the tip of the ear along the posterior border between the index tinger and thumb of the left hand and plunge the needle directly into the vein and discharge its contents.

Bacteria and substances containing bacteria, are introduced into animals in many other ways than those which have been here mentioned, such as being breathed directly into the lungs, or inserted through an opening made into the trachea, into the stomach and intestines by laparotomy, into the interior of the eye by incision, etc., etc., but these are only required in special experimentation, and a full description of them, together wilh minute technical instructions, will be found in the larger text-books on bacteriology.

Whenever possible to do so, only pure cultures of bacteria, diluted, if necessary, with sterile buillon or water, should be used in inoculation experiments, otherwise one is very apt to have a mixed intection instead of the results of a single germ.

The strictest attention should always be paid to the observance of surgical asepsis in all of the above operations, in order that mixed infection. may not occur to mar our results and invalidate our observations.

(Next article in the December number.)

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